The present disclosure relates to load cells and particularly, to load cells that generate signals indicative of loads applied to the load cells. More particularly the present disclosure relates to a load cell apparatus having a gap measuring device.
It is well known to use load cells to sense loads. Some conventional load cells include a block (also known as a load beam) and one or more strain gages mounted to the block. Deflection of the block due to an applied load changes the shape of the strain gages resulting in a change in the resistance of the strain gages. Generally, a known input voltage is applied to the strain gages and an output signal from the strain gages varies as the resistance of the strain gages vary to provide a signal indicative of the load applied to the load cell. Some conventional load cells include other types of sensors, such as optical sensors and capacitive sensors, rather than strain gages, that measure the size of gaps between elements of a load cell system. It is desirable, of course, for load cells to sense applied loads with a high degree of accuracy and repeatability.
According to the present disclosure, a load cell apparatus for use with a structure includes a cell block that deflects in response to an applied load. The load cell apparatus further includes a transducer coupled to the cell block. The transducer is adapted to measure a distance across a gap defined between the transducer and the structure.
In some embodiments, the transducer emits electromagnetic energy toward a target surface. The transducer of some of these embodiments uses shaped electromagnetic field technology to measure the distance across the gap. In some embodiments, the structure to which the load cell apparatus is coupled comprises a mounting bar which, in turn, is adapted to be coupled to another structure. In such embodiments, the cell block is coupled to the mounting bar and the gap is defined between the transducer and the mounting bar. In other embodiments, the cell block is adapted to couple to a structure and the transducer is coupled to the structure rather than the cell block. In such embodiments, the gap is defined between the transducer and the cell block.
In some embodiments, the load cell apparatus includes a stud extending from a movable portion of the cell block. In such embodiments, the cell block couples to a first structure and the stud engages a mount that is coupled to a second structure. In illustrative embodiments, the stud extends from a first planar face of an end portion of the cell block and the transducer includes an end face that is substantially coplanar with a second planar face of the end portion of the cell block. In such illustrative embodiments, the first planar face is perpendicular to the second planar face.
Also according to the present disclosure, a load cell apparatus includes a cell block supported with respect to a structure. The cell block includes a movable portion that is spaced apart from the structure such that a gap is defined between the movable portion and the structure. The load cell apparatus includes a transducer that is configured to measure a distance across the gap. The movable portion moves and the distance changes in response to a load being applied to the movable portion. In some embodiments, the transducer is coupled to the cell block and in other embodiments, the transducer is coupled to the structure.
Further according to the present disclosure, a load cell apparatus includes two elements defining a gap therebetween. At least one of the elements is deflectable under a load to vary the gap. The load cell apparatus includes a transducer for measuring the gap change in response to the load.
In illustrative embodiments, an electric circuit is coupled to the transducer to receive an output signal from the transducer. The output signal from the transducer is indicative of the distance across the gap and the load applied to the load cell. In the embodiments in which the transducer emits electromagnetic energy toward a target surface, including those embodiments using shaped electromagnetic field technology, the electric circuit provides an input signal to the transducer to generate the electromagnetic energy. In some embodiments, the electromagnetic energy is generated in pulses. In some embodiments, the electric circuit is mounted to the cell block and in other embodiments the electric circuit is mounted to a structure other than the cell block.
Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrated embodiments exemplifying the best mode of carrying out the invention as presently perceived.